Stalked crop harvesting header structure

ABSTRACT

A stalked crop harvesting header comprising multiple harvesting units each comprising a pair of deck plates defining a channel, a pair of snapping rollers mounted below the deck plates and adapted to pull stalks downwardly through the channel, a pair of gathering chains provided with cams, the gathering chains extending between a first pair of gears located at a front end of the harvesting unit and a second pair of gears located at a back end of the harvesting unit, wherein each harvesting unit further comprises a pair of stalk guiders positioned to rotate around axes coinciding with respective axes of the first pair of gears, wherein the stalk guiders each comprise an upper stalk guiding wheel and a lower stalk guiding wheel which are interconnected, and wherein a cutting element is provided below the lower stalk guiding wheel to cut stalks while being guided by the stalk guider.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to Belgian Application No. 2015/5552filed Aug. 31, 2015, the contents of which are incorporated herein byreference.

BACKGROUND OF THE INVENTION

The present invention relates to a stalked crop harvesting header for anagricultural vehicle.

Stalked cropped harvesting headers are formed to pull stalks downwardbetween a pair of deck plates that are spaced in such a manner that thestalk can substantially freely move through the channel formed by thedeck plates while the corn head or other crop material heads areretained by the deck plates. Different aspects of such harvestingheaders have been described. For example, WO 2012/152 866 describes thesnapping rollers that are used to grasp and pull stalks downward throughthe channel. EP 2 412 228 describes a header wherein the spacing betweenthe deck plates is adjustable to optimize the operation of the header.These documents describe headers that are row sensitive. Row sensitiveheaders are headers that operate correctly only when the channels of themultiple harvesting units in the header are aligned with the rows ofstalked crop on the field. As a result of aligning the channel with thestalked crop, the stalked crop can enter the channel while the stalkedcrop is still rooted in the ground. In conventional row sensitivestalked crop harvesting headers, this ensures correct operation of theheader.

A drawback of the known crop harvesting headers is that they onlyperform correctly when the rows of crop are aligned with the channels ofthe harvesting units. This places a burden on the driver of theagricultural vehicle because care should be taken that the vehicle issteered so that the channels are constantly aligned with the rows ofstalked crop during the harvesting. Another drawback is that stalkedcrop can be sown in rows with different spacing. To be able to harvestrows with different spacings, different headers are required wherein thedistance between the channels match the spacing between the rows ofcrop. To overcome these drawbacks of row sensitive harvesting, rownon-sensitive harvesting headers have been proposed.

U.S. Pat. No. 6,119,443 describes a row non-sensitive harvesting header.A drawback of this header is that the mechanical structure is complex sothat the header is expensive. Furthermore, because stalks are cut fromthe ground surface before entering the channel, the guiding of thestalks proves to be difficult resulting in the possibility of congestionof an entrance of the channel. In this context, tests have shown thatstalks can experience a high resistance against entering the channel andentering the snapping rollers. Due to this resistance, the stalks chokethe front end of the channels thereby ceasing the correct operation ofthe header.

US 2014/005 994 describes a row non-sensitive header wherein the stalksare caught at a higher level thereby preventing the stalks to fall downafter being cut from the ground. This improves the movement of thestalks in between the snapping rollers and the channel, however it makesthe header significantly more complex and expensive.

It is an object of the present invention to provide a row non-sensitivestalked crop harvesting header with a higher operational reliability andan improved structure.

SUMMARY OF THE INVENTION

To this end, the invention provides a stalked crop harvesting headercomprising multiple harvesting units, wherein each harvesting unitcomprises a pair of deck plates defining a channel, a pair of snappingrollers mounted below the deck plates and adapted to grasp and pullstalks downwardly through the channel, a pair of gathering chainsprovided with cams, the gathering chains extending between a first pairof gears located at either side of the front end of the harvesting unitand a second pair of gears located at a back end of the harvesting unit,the gathering chains being provided for conveying stalks along thechannel, wherein each harvesting unit further comprises a pair of stalkguides positioned to rotate around axes coinciding with respective axesof the first pair of gears, wherein the stalk guides each comprising anupper stalk guiding wheel and a lower stalk guiding wheel which areoperationally connected to each other for guiding stalks in a movementtowards the channel, and wherein a cutting element is provided below thelower stalk guiding wheel to cut stalks while being guided by the stalkguides.

The stalked crop harvesting header of the invention is row non-sensitivedue to the cutting elements which are provided below the stalk guidingwheels. These cutting elements cut stalks from the ground surface sothat stalks that are not aligned with the channel can correctly beguided towards the channel via the stalk guides. Furthermore, the stalkguides comprise an upper and a lower stalk guiding wheel. Particularlydue to the connection between the upper and the lower stalk guidingwheel, the structure of the harvesting header is significantlysimplified. Since the stalk guides comprise an upper and a lower guidingwheel, the stalk is held at two locations along the height of the stalk,so that falling of the stalk after cutting is prevented. Thereby stalkscan be guided in a movement towards the channel. This improves theoperational reliability of the header. Guiding the stalks at twodifferent heights via a lower and an upper guiding wheel towards thechannel has as a result that reliable guidance is obtained so thatclogging of the channel entrance is maximally prevented.

Preferably, each gear of the first pair of gears rotates around arespective shaft, and wherein the respective shafts are furtherconnected to corresponding upper stalk guiding wheels and lower stalkguiding wheels so that the upper and lower stalk guiding wheels areinterconnected via the respective shafts. Due to the connection of thefirst pair of gears with the respective stalk guides, the stalk guidesrotate simultaneously with the first pair of gears. Therefore, due tothe connection, the stalk guides are driven via the first pair of gearsso that no separate actuator or motor should be provided at the frontend of the harvesting unit. Typically, the gathering chain is actuatedvia a motor or actuator connected to the second pair of gears. Thisfurther simplifies the structure of the harvesting units. Furthermore,the direct connection proves to be an advantage since the speed withwhich stalks are guided by the stalk guides in synchronized with thespeed with which stalks are moved through the channel by the gatheringchain. This synchronization prevents clogging and ensures correctoperation of the harvesting header.

Preferably, each gathering chain is further provided to extend along apositioning gear positioned at either side of a front end of thechannel. By guiding the gathering chain, in addition to the first andsecond gear, along a positioning gear, particularly the position of thefirst gear can be more freely chosen without affecting the correctoperation of the gathering chain. When the axes of the stalk guides arealigned with the axes of the first gears of the gathering chain, itmight be preferable to position the first gear more offset with respectto the center plane of the harvesting unit, thereby enlarging the extentof the stalk guides. However without a positioning gear, this couldresult in the gathering chain being positioned too far from the channelto efficiently force the stalks in a movement along the channel. Withthe positioning gear, the location of the gathering chain with respectto the channel can be determined irrespective of the offset of the firstgear.

Preferably, a distance between the positioning gear axis and thecorresponding front gear axis is approximately equal to the radius ofthe upper guiding wheel. Thereby, the positioning gear is located at aperiphery of the upper guiding wheel. Since the positioning gear islocated at a front end of the channel, this location of the positioninggear optimizes the transferring of the stalks, namely stalks can beguided by the stalk guides towards an entrance of the channel, where thestalks are then forced in a movement through the channel via thegathering chains.

Preferably, each stalk guiding wheel is disk-shaped and comprisesindentations at a periphery of the disk. Such disk-shaped guiding wheelproves to be an efficient way of guiding stalks. The disk-shape allows asimple structure of the harvesting unit, is easy to actuate and whenprovided with indentations, is able to guide stalks by catching thestalks in the guides thereby guiding stalks with high precision.Thereby, the indentations are preferably adapted to capture at least onestalk such that the stalk extends within the peripheral edges of thedisk-shaped wheel.

Preferably, the header comprises multiple lane determining elementsextending from a front end of the header in a forward driving direction,wherein the multiple lane determining elements separate the multipleharvesting units from each other in the lateral direction. The lanedetermining elements ensure that stalks are prevented from arrivingbetween two harvesting units, which would have as a result that thesestalks are not processed. Particularly in row non-sensitive harvestingheaders, these lane determining elements prove to be advantageous forthis purpose. A stalk which is caught between two lane determiningelements will thereby automatically, due to the forward movement of theharvester carrying the header, be caught by the stalk guides. Thisensures correct further processing of the stalks by the harvesting unit.

Preferably, the pair of upper stalk guiding wheels extend, in thelateral direction of the harvesting unit over a distance that is largerthan the spacing between adjacent lane determining elements. Thereby thecomplete front end of the header is covered by stalk guiding wheels sothat stalks are, irrespective of their position at the front end of theheader, always caught by a guiding wheel.

Preferably, each harvesting unit is further provided with a stalkchopper below the snapping rollers for chopping the stalk into pieceswhen it is pulled downward. Via the stalk chopper, the residue of thestalked crop material is cut into small pieces so that the harvester isin its forward movement not hindered by the residue.

Preferably, each cutting element is formed as a stalk cutting wheelrotatably mounted about an axis coinciding with the respective axis ofthe first pair of gears, wherein the stalk cutting wheel is connected tothe respective first pair of gears via transmission device so that thegear rotates at a first rotational speed while the stalk cutting wheelrotates at a second rotational speed which is higher than the firstrotational speed. Tests have shown that a rotating stalk cutting wheelis much more efficient in cutting the stalks compared to a fixed cuttingknife. By powering the rotating stalk cutting wheel via a transmissiondevice connected to the first pair of gears, no additional actuator ormotor should be provided, which further simplifies the structure of theharvesting header. Thereby preferably, the transmission device is formedas a planetary gearbox.

Preferably, the stalk guiding guides each comprise a frame carrying theupper stalk guiding wheel and the lower stalk guiding wheel, wherein theframe further comprises a protrusion between the upper and the lowerstalk guiding wheels, which protrusion comprises a support for carryinga respective front end of the snapping rollers. This frame can holdtogether multiple components so that the structure of the harvestingheader can be made simple.

The invention further relates to an agricultural harvester carrying astalked crop harvesting header according to the above-describedinvention. The invention further relates to a harvesting unit adaptedfor being part of a stalked crop harvesting header, wherein theharvesting unit comprises a pair of deck plates defining a channel, apair of snapping rollers mounted below the deck plates and adapted tograsp and pull stalks downwardly through the channel, a pair ofgathering chains provided with cams, the gathering chains extendingbetween a first pair of gears located at either side of the front end ofthe harvesting unit and a second pair of gears located at a back end ofthe harvesting unit, the gathering chains being provided for conveyingstalks along the channel, wherein each harvesting unit further comprisesa pair of stalk guides positioned to rotate around axes coinciding withrespective axes of the first pair of gears, wherein the stalk guideseach comprising an upper stalk guiding wheel and a lower stalk guidingwheel which are interconnected, and wherein a cutting element isprovided below the lower stalk guiding wheel to cut stalks while beingguided by the stalk guides. Multiple of these harvesting units builttogether form the harvesting header which is described above. Theeffects and advantages described above in relation to the harvestingheader of the invention are a direct result of the technical features ofthe harvesting unit. Therefore these effects and advantages equallyapply to the harvesting unit, as will be understood by the skilledperson.

BRIEF DESCRIPTION OF THE DRAWINGS

Some embodiments of apparatus and/or methods in accordance withembodiments of the present invention are now described, by way ofexample only, and with reference to the accompanying drawings, in which:

FIG. 1 illustrates a side view of an agricultural vehicle carrying astalked crop harvesting header according to an embodiment of theinvention;

FIG. 2 illustrates a top view of the harvesting header of FIG. 1;

FIG. 3 shows a perspective view of two adjacent harvesting units of theharvesting header of an embodiment of the invention;

FIG. 4 shows a close-up of a front end of one side of one of theharvesting units of FIG. 3;

FIG. 5 shows a cross-section of a front end of one of the harvestingunits of FIG. 3; and

FIG. 6 shows a horizontal cross-section of the frame comprising aplanetary gearbox as is usable in a harvesting unit according to anembodiment of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a stalked crop harvesting header 1 mounted to anagricultural vehicle 2, preferably an agricultural harvester. Thereby,the figure illustrates how the agricultural vehicle 2 is driven over afield with stalked crop 11. The header 1 is adapted to harvest thestalked crop 11, and to gather at least a part of the harvested crop,for example the crop elements, into the body 7 of the agriculturalvehicle 2. The gathered crop elements can be further processed in thebody 7 of the agricultural vehicle 2.

The header 1 is connected to the agricultural vehicle 2 via a feeder 3and an actuator 6. The feeder 3 and the actuator 6 are connected to aheader mounting plate 5, which header mounting plate 5 carries theheader 1. Crop elements gathered by the header 1 are transported to thebody 7 of the agricultural vehicle 2 via the feeder 3.

The header 1 comprises multiple lane determining elements 8. These lanedetermining elements 8 are formed as protrusions at a front end of theheader 1 extending substantially in the forward driving direction of thevehicle 2. The lane determining elements are positioned between adjacentharvesting units 10 so that a respective lane is formed for each of theharvesting units 10. Thereby, the lane determining elements 8 functionas a guide for the stalked crops on the field to guide each of thestalked crops into a lane and towards a harvesting unit 10. This isfurther shown and explained in relation to FIG. 2.

Once a stalked crop 11 is caught in the harvesting unit 10, the stalkedcrop is cut from the ground surface and is pulled downward, as isillustrated in FIG. 1 with crop element 11′. Preferably the stalk of thestalked crop is chopped while pulling the stalk downward. The cropelements, for example the corn crops, are torn away from the stalkduring the pulling downward of the stalk. Thereby crop elements are atleast partially separated from residue by the header. Crop elements arethen gathered by screw conveyor 9. Screw conveyor 9 conveys the croptowards the feeder 3 so that the crop can be further processed in thebody 7 of the agricultural harvester 2.

FIG. 2 shows a top view of the header 1 of FIG. 1. FIG. 2 shows how theheader 1 extends over a significant width which is at least larger thanthe width of the agricultural harvester 2. The header 1 comprisesmultiple harvesting units (10 a, 10 b, . . . , 10 g). When the header 1is driven over a field with stalked crop, the stalked crop is guidedtowards one of the harvesting units via the lane determining elements 8,as will be clear to the skilled person from FIG. 2. Each harvesting unit10 comprises a channel 12. Thereby, the harvesting units are providedfor harvesting the stalked crop by processing the stalked crop in thechannel, as will be described hereunder. FIG. 2 further shows the screwconveyor 9 at a back end of the header 1, and wherein the screw conveyor9 is formed to transport the crop elements from the multiple harvestingunits to a central opening (not shown) for transferring the cropelements to the feeder 3 and further to the agricultural vehicle 2.

FIG. 3 shows two harvesting units in more detail. Thereby, it can beseen in FIG. 3 that the channel 12 of each harvesting unit 10 is definedby a set of deck plates 13. Preferably, two deck plates 13 are providedat a predetermined distance from one another to obtain a channel havinga width which is determined by the predetermined distance. The deckplates 13 can have a predefined position, or can be mounted moveablewith respect to each other so that the width of the channel between thedeck plates can be adapted. In sophisticated harvesting headers, thedistance between the deck plates can be automatically adapted based onsensor measurements relating to the harvesting process to therebyoptimize the harvesting operation.

Above the deck plates 13, each harvesting unit 10 comprises a pair ofgathering chains 14. Thereby, a first gathering chain 14 is provided ata first lateral side of the channel while another gathering chain 14′ isprovided at a second lateral side of the channel. Furthermore, eachgathering chain of the pair of gathering chains extends between a first,front gear 15 and a second, back gear 16. Thereby, front and back aredefined in relation to the relative intended movement of the stalkedcrop elements through the channel, whereby front relates to the positionwhere the stalked crop element arrives first in the channel and whereinback relates to the position where the stalked crop elements are movedtowards when moving through the channel. The gathering chain ispreferably provided with cams 29 which are defined as lateralprotrusions from the chain which are able to at least partially hookbehind stalked crop elements moving through the channel, so that thegathering chain is able, via the cams 29, to pull stalked crop elementsthrough the channel from a front end towards a back end of the channel.

To optimize the gathering chain operation, further chain positioninggears can be provided for further defining the position of the gatheringchain with respect to the channel defined by the deck plates 13. Two ofsuch additional gears for each gathering chain are shown in FIG. 3. Eachgathering chain 14 is driven at a gathering chain speed in such a mannerthat the cams 29 transport the stalked crop elements through thechannel. Thereby, the gathering chain speed can be predetermined or ispreferably related to the forward driving speed of the agriculturalvehicle carrying the stalked crop harvesting header 1. The gatheringchain speed can be further related to the density of stalked cropelements 11 on the field. Further preferably, the gathering chain speedis adapted based on sensor measurements relating to the harvestingprocess. The gathering chains 14 are preferably actuated at a back ofthe harvesting unit. In the example of FIG. 3, preferably the secondpair of gears 16, 16′ are provided with a rotary actuator for drivingthe gathering chains. An advantage of driving the gathering chains at aback of the harvesting unit, is that there is more space for actuatorsat the back of the harvesting unit.

Each harvesting unit 10 preferably further comprises a pair of stalkguides 17, 18. Thereby the stalk guides 17, 18 are adapted to guide allstalks in the harvesting unit lane, which lane is defined by the lanedetermining elements 8, towards a lateral center of the harvesting unit10 so that the stalks can be processed in the channel. Consequently,each harvesting unit 10 has a pair of stalk guides s 17, 18 at eitherside of the front end of the channel. The stalk guides 17, 18 preferablycooperate with cutting element 19 positioned underneath the stalk guides17, 18 so that when stalks are guided to the lateral center of theharvesting unit, the stalks can be cut from the ground surface. As aresult of cutting the stalks from the ground surface, moving stalkstowards the center is possible without cracking or bending the stalks.

Each one of the pair of stalk guides of a harvesting unit preferablycomprises a frame 20 adapted to carry stalk guiding elements and cropprocessing elements of the harvesting units, as will be furtherdescribed hereunder.

Each one of the pair of stalk guides preferably comprises an upper stalkguiding wheel 17 and a lower stalk guiding wheel 18. The upper stalkguiding wheel is preferably mounted at an upper end of the frame 20while the lower stalk guiding wheel is preferably mounted at a lower endof the frame 20. In this manner, the frame 20 determines the distancebetween the upper 17 and the lower 18 stalk guiding wheel. Each stalkguiding wheel 17, 18 is preferably disk-shaped wherein the periphery ofthe disk is provided with multiple indentations. Thereby, eachindentation is shaped to catch and hold at least one stalk of thestalked crop 11. The indentations can be formed to be able to enclosemultiple stalks at the same time. In this manner, when the stalk guidingwheels rotate, the disks tend to catch and transport the stalks along atleast a part of the front end of the disks.

The frame 20 can be shaped, or provided with an element, to push stalksout of the indentations of the stalk guiding wheels when the stalksarrive at an entrance of the channel 12 of the harvesting unit 10. Theupper and lower stalk guiding wheels 17, 18 preferably show a distancebetween each other of at least 5 centimeters, more preferably of atleast 8 centimeters, most preferably of at least 10 centimeters. Furtherpreferably, the upper and lower stalk guiding wheels 17, 18 areinterconnected via a shaft. As a result of the interconnection via theshaft, the upper stalk guiding wheel and the lower stalk guiding wheelrotate about the same axis and rotate at the same speed. This improvescorrect guidance of the stalks. The shaft interconnecting the guidingwheels is preferably further connected to the front gear 15 of thegathering chain 14. This has as a direct result that no actuator ormotor should be provided at the front end of the harvester for drivingthe guiding wheels 17, 18. Namely, the gathering chain is driven via therear gear 16, and this rotation is transferred via the gathering chain14 to the front gear 15 which can further transmit its rotation via theshaft to the upper and lower guiding wheel 17, 18. Another result of theconnection between the gathering chain and the stalk guides is that thespeed of the gathering chain 14 is directly linked to the rotationalspeed of the guiding wheels. In practice, this proves to be an advantagesince a faster rotation of the guiding wheels, and thereby fastermovement of stalks towards the channel, is followed by a faster movementof the stalks through the channel by the gathering chain 14. Thereby,stalk collecting speed, determined by the speed of the guiding wheels,is correlated to the stalk processing speed that is determined by thespeed of the gathering chain.

Preferably, a stalk cutting wheel 19 is provided at a lower end of theframe 20, more preferably below the lower stalk guiding wheel 18.According to a first embodiment, the stalk cutting wheel is formed as aknife which is mounted to the frame in a fixed, stand still, position.Thereby the stalk guiding wheels force the stalks along the knifes sothat the stalks are cut. According to a preferred embodiment, the stalkcutting wheel is driven and operates as a blade saw. Thereby, the stalkcutting wheel is preferably disk-shaped, wherein teeth can be providedat the periphery of the disk for improving cutting properties. Thecutting wheel preferably rotates around the same axis as thecorresponding stalk guiding wheels. However, the cutting wheelpreferably rotates significantly faster than the stalk guiding wheels.Such faster rotation can be obtained by providing a separate actuatorfor the cutting wheel. However, preferably the cutting wheel isconnected to the stalk guiding wheels via a gearbox. The gearbox ispreferably located inside the frame 20. The gearbox can be formed as aplanetary gearbox, as is shown in FIG. 6.

The frame 20 is further preferably provided with a protrusion comprisinga support for carrying a front end of the snapping rollers, which aredescribed hereunder in relation to FIG. 4. In this manner, the frame 20is in the preferred embodiment as shown in FIG. 3 multifunctional andcarries the front gear 15 of the gathering chain 14, the stalk guides17, 18, defines the distance between the upper guiding wheel 17 and thelower guiding wheel 18, carries the transmission elementsinterconnecting the guiding wheels and the cutting wheel 19, and forms asupport for a front end of the snapping rollers 21.

FIG. 4 shows a perspective view of one side of the channel 12. Thereby,FIG. 4 only shows one element from each of the pairs of elements thatform part of the harvesting unit 10. It will be clear that in operationthe two elements of the pairs cooperate together to obtain correctoperation of the harvesting unit, as will be further shown in FIG. 5.However, construction related issues and choices can be described basedon FIG. 4 since this is substantially the same for the two lateral sidesof the harvesting unit. Thereby, the skilled person will understand thata plane of symmetry can be defined at a center of the channel 12, andthe harvesting unit 10 is built largely symmetrical about the plane ofsymmetry.

FIG. 4 shows the above described gathering chain 14, guided over a frontgear 15. FIG. 4 further shows the upper stalk guiding wheel 17 and thelower stalk guiding wheel 18, and a frame 20 being mounted between theupper and lower stalk guiding wheel. Below the lower stalk guiding wheel18, the stalk cutting wheel 19 is provided. FIG. 4 further shows one ofthe two deck plates 13. Below each one of the deck plates 13 (only onedeck plate 13 is shown in FIG. 4), a snapping roller 21 is mounted. Thepair of snapping rollers is thereby formed and positioned with respectto each other to be able to grasp the stalks in the channel, and to pullthese stalks downwards by rotating the snapping rollers. Thereby, stalksare pulled downwards in the channel and consequently pulled downwardbetween the deck plates. The distance between adjacent deck plates 13 ischosen so that the stalks can freely pass through the deck plates whilethe crop elements are retained by the deck elements 13. This is theresult of the crop elements typically being significantly larger inwidth than the stalks. In this manner, the harvesting unit obtains aseparation between stalks and crop elements. Snapping rollers are knownin the art and therefore the technical features of these rollers are notdescribed in more detail in this description.

The snapping rollers 21 are preferably provided with a tapered thread ata front end of each snapping roller. The tapered thread is provided topull stalks, arriving at a front end of the channel, in between thesnapping rollers 21. Tests have shown that snapping rollers, becausethey grasp and pull down the stalks, form a resistance for stalks toenter in between the rollers. Because the harvesting units of thepresent invention cut the stalks at a lower end, such resistance by thesnapping rollers could have as a result that the stalks at least notdirectly enter the snapping rollers thereby choking the front end of thechannel. The tapered thread at a front end of the snapping rollersprevents this by guiding and forcing the stalks in between the snappingrollers 21.

The snapping rollers 21 are rotatebly mounted around respective axis sothat each snapping roller rotates around a shaft. This shaft is born ata back end of the snapping rollers and at a front end of the snappingroller. Preferably, the snapping rollers are actuated at a back end ofthe snapping rollers while the shaft is only held in place at a frontend of the snapping roller 21. FIG. 4 illustrates how the front end ofthe shaft of the snapping roller 21 is supported by the frame 20. In theembodiment of FIG. 4, a supporting element 23 is rigidly mounted toframe 20, particularly to a protrusion 24, which protrusion isspecifically provided for mounting the supporting element 23 at theframe 20.

The frame 20 has a predetermined shape which is adapted for performingmultiple functions. The frame 20 extends between the upper and the lowerstalk guiding wheel 17, 18 to mount these guiding wheels at apredetermined distance from each other. Furthermore, the frame 20preferably comprises the gear elements connecting the stalk guidingwheels 17, 18 with the stalk cutting wheel 19 so that the stalk cuttingwheel 19 can rotate at a significantly higher speed than the guidingwheels. A front end of the frame, whereby front end is considered inrelation to the normal moving direction of the harvesting header,extends significantly less to the front than the stalk guiding wheels.As a result, the periphery of the stalk guiding wheels can manipulatethe stalks without interference of the frame 20. At an entrance of thechannel, the frame 20 is shaped to push stalks out of the guiding wheels17, 18. Therefore, the frame 20 comprises a stalk pushing element 25which is shaped to form a funnel for the channel entrance. When a stalkis grasped by the stalk guides, and is held in an indentation of theguiding wheels, rotation of the guiding wheels will move the stalktowards the funnel, where the stalk is pushed out of the indentation bythe funnel shape. In this manner, stalks are guided to the channelentrance, and are forced into the channel.

FIG. 4 further shows a gathering chain positioning gear 26 which isprovided near an entrance of the channel to guide the gathering chainalong the channel. This positioning gear 26 thereby allows the firstgear 15 to show an offset with respect to the channel, thereby allowingthe stalk guiding wheel 17, 18 to be aligned with and driven by thefirst gear 15, while the gathering chain 14 is close enough to thechannel for the protrusions to be able to hook behind the stalks andforce the stalks through the channel.

FIG. 4 further shows how the front end of the snapping roller 21 ismounted to the frame 20, considered in the direction of the channel, atthe location of the guiding wheel axis. Furthermore, the front end ofthe snapping roller 21 is mounted within the periphery of the guidingwheels 17, 18. As a result, a front end of the snapping roller 21extends at least partially, preferably completely between the upperstalk guiding wheel 17 and the lower stalk guiding wheel 18. This provesto be a compact and space efficient manner of mounting the differentelements together. A further effect is that the guiding wheels can holdand guide the stalks while the stalks enter in between the snappingrollers 21. As described above, entering in between the snapping rollers21 can be difficult for a stalk since there is a resistance againstentering. By mounting the front end of the snapping rollers between theupper and the lower stalk guiding wheel, stalks are not released in themovement from the stalk guiding wheels to the channel. This results in ahighly reliable operation wherein choking of the entrance of the channelis avoided.

FIG. 5 shows a cross-section of a front end of the harvesting unit. Thecross-section is made substantially at the axes of the front gears 15,15′ of the gathering chains of the harvesting unit. The cross-sectionillustrates how the front gear 15 is connected, via element 27 whichwill be described hereunder, to the upper stalk guiding wheel 17 and thelower stalk guiding wheel 18. By the interconnection of the lower stalkguiding wheel 18, upper stalk guiding wheel 17 and front gear 15, thelatter can rotate simultaneously.

FIG. 5 further shows how the frame 20 comprises a planetary gear systemwherein the frame 20 operates as a ring gear while element 27 operatesas planetary gear elements and wherein element 28 operates as a sunwheel. Thereby, the planetary gear system can be designed in such amanner that the sun wheel 28 rotates significantly faster than theplanetary gear elements 27. The planetary gear elements 27 are connectedto the first gear 15 and the upper stalk guiding wheel 17 and the lowerstalk guiding wheel 18, while the sun wheel is connected to the stalkcutting wheel 19. Thereby, actuating the gathering chain 14 has as aresult that the front gear 15 is rotated, thereby also rotating thestalk guides 17, 18, and driving the gear elements 27, 28 so that alsothe stalk cutting wheel 19 is driven. Thereby, the stalk cutting wheel19 is driven at a significantly higher rotational speed than the stalkguiding wheels 17, 18.

The FIG. 5 shows that the pair of upper stalk guiding wheels 17, 17′show an overlap in the lateral direction of the harvesting unit.Therefore, in the embodiment of FIG. 5, the left upper stalk guidingwheel 17 is mounted a little higher than the right one of the pair ofupper stalk guiding wheels 17′. In this manner, the upper stalk guidingwheels 17 and 17′ can have an overlap without colliding.

It will be clear for the skilled person that in the example of FIG. 5the elements of the harvesting unit 10 shown on the left hand siderotate in a first direction, for example clockwise when looking topdown, while the elements on the right hand side of the figure rotate inan opposite direction, for example counterclockwise when considered topdown. As a result, both the elements on the left hand side as well asthe elements on the right hand side move the stalks towards the channelwhich is located centrally in the lateral direction. In the presentdescription, corresponding elements on the left and on the right handside are considered as a pair. Thereby, each harvesting unit has a pairof first gears 15, 15′, a pair of upper stalk guiding wheels 17, 17′, apair of lower stalk guiding wheels 18, 18′, a pair of stalk cuttingwheels 19, 19′, a pair of frames 20, 20′, etc. These pairs of elementscooperate to guide the stalks towards and through the channel of theharvesting unit.

FIG. 5 also illustrates the pair of snapping rollers 21, 21′. Eachroller is mounted via a corresponding mounting element 23, 23′ to thecorresponding frame 20, 20′. Thereby, the front end of each snappingroller 21 is located at least partially between the upper and the lowerstalk guiding wheels 17, 18. The effect of this position of the snappingrollers 21 with respect to the stalk guiding wheels is described above.

FIG. 6 illustrates an example of the planetary gearbox which is suitableto be built into the frame 20. The figure shows the ring wheel 20,formed by the frame, shows the sun wheel 28, which will typically rotateat a high rotational speed compared to the planetary gear elements 27.The skilled person will understand how such planetary gearbox operates,how such planetary gearbox can be designed and how such planetarygearbox can be built into the frame 20 as described above.

Based on the figures and the description, the skilled person will beable to understand the operation and advantages of the invention as wellas different embodiments thereof. It is however noted that thedescription and figures are merely intended for understanding theinvention, and not for limiting the invention to certain embodiments orexamples used therein. Therefore it is emphasized that the scope of theinvention will only be defined in the claims.

The invention claimed is:
 1. A stalked crop harvesting header comprisingmultiple harvesting units, wherein each harvesting unit comprises: apair of deck plates defining a channel, a pair of snapping rollersmounted below the deck plates, and a pair of gathering chains providedwith cams, the gathering chains extending between a first pair of gearslocated at either side of the front end of the harvesting unit and asecond pair of gears located at a back end of the harvesting unit,wherein each harvesting unit further comprises: a pair of stalk guidespositioned to rotate around axes coinciding with respective axes of thefirst pair of gears, wherein the stalk guides each comprising: an upperstalk guiding wheel and a lower stalk guiding wheel which are coupled toeach other, and wherein a cutting element is provided below the lowerstalk guiding wheel to cut stalks, wherein each said cutting element isformed as a stalk cutting wheel rotatably mounted about an axiscoinciding with the respective axis of the first pair of gears, whereinthe stalk cutting wheel is connected to the respective first pair ofgears via a transmission device so that the gear rotates at a firstrotational speed while the stalk cutting wheel rotates at a secondrotational speed which is higher than the first rotational speed.
 2. Thestalked crop harvesting header according to claim 1, wherein each gearof the first pair of gears rotates around a respective shaft, andwherein the respective shafts are further connected to correspondingupper stalk guiding wheels and lower stalk guiding wheels via therespective shafts.
 3. The stalked crop harvesting header according toclaim 1, further comprising a positioning gear, wherein the gatheringchain is further provided to extend along the positioning gearpositioned at either side of a front end of the channel.
 4. The stalkedcrop harvesting header according to claim 3, wherein a distance betweenan axis of the positioning gear and an axis of the corresponding gear ofthe first pair of gears is approximately equal to the radius of theupper guiding wheel.
 5. The stalked crop harvesting header according toclaim 1, wherein each stalk guiding wheel is disk-shaped and comprisesindentations at a periphery of the disk.
 6. The stalked crop harvestingheader according to claim 1, wherein the header comprises multiple lanedetermining elements extending from a front end of the header in aforward driving direction, wherein the multiple lane determiningelements separate the multiple harvesting units from each other in thelateral direction.
 7. The stalked crop harvesting header according toclaim 6, wherein the outer diameter of the pair of upper stalk guidingwheels extend, in the lateral direction of the harvesting unit over adistance that is larger than the spacing between adjacent lanedetermining elements.
 8. The stalked crop harvesting header according toclaim 1, wherein the transmission device is formed as a planetarygearbox.
 9. The stalked crop harvesting header according to claim 1,wherein the stalk guides each comprise a frame carrying the upper stalkguiding wheel and the lower stalk guiding wheel, wherein the framefurther comprises a protrusion between the upper and the lower stalkguiding wheels, which protrusion comprises a support for carrying arespective front end of the snapping rollers.
 10. An agriculturalharvester carrying a stalked crop harvesting header according toclaim
 1. 11. A stalked crop harvesting header comprising: a conveyor;and at least one harvesting unit having a front end and a back end, theat least one harvesting unit comprising: at least two deck platesdefining a channel; at least two snapping rollers mounted below the atleast two deck plates; at least two first gears located at either sideof the front end of the at least one harvesting unit; at least twosecond gears located at either side of the back end of the at least oneharvesting unit; at least two gathering chains provided with cams, theat least two gathering chains extending between respective ones of theat least two first gears and respective ones of the at least two secondgears, the at least two gathering chains; at least two stalk guiderspositioned to rotate around axes coinciding with axes of respective onesof the at least two first gears, each of the at least two stalk guiderscomprising an upper stalk guiding wheel and a lower stalk guiding wheelwhich are coupled to each other; and a cutting element disposed belowthe lower stalk guiding wheels of the at least two stalk guiders to cutstalks, wherein the cutting element comprises a first stalk cuttingwheel and a second stalk cutting wheel, wherein each of the first andsecond stalk cutting wheels is rotatably mounted about an axiscoinciding with an axis of a respective one of the at least two firstgears, wherein each of the first and second stalk cutting wheels isconnected to the respective one of the at least two first gears via atransmission so that the respective one of the at least two first gearsrotates at a first rotational speed while the each of the first andsecond stalk cutting wheels rotates at a second rotational speed whichis higher than the first rotational speed.
 12. The stalked cropharvesting header according to claim 11, wherein each gear of the atleast two first gears rotates around a respective shaft, and wherein therespective shafts are further connected to corresponding ones of theupper stalk guiding wheels and corresponding ones of the lower stalkguiding wheels so that the upper and lower stalk guiding wheels of eachof the at least two stalk guiders are interconnected via the respectiveshaft.
 13. The stalked crop harvesting header according to claim 11,further comprising of at least two positioning gears, wherein the atleast one harvesting unit further comprises the at least two positioninggears positioned at either side of the front end of the channel, andwherein each of the at least two gathering chains extends along arespective one of the at least two positioning gears.
 14. The stalkedcrop harvesting header according to claim 13, wherein a distance betweenan axis of each of the at least two the positioning gears and an axis ofa corresponding one of the at least two first gears is approximatelyequal to a radius of the upper guiding wheel of a corresponding one ofthe at least two stalk guiders.
 15. The stalked crop harvesting headeraccording to claim 11, wherein each of the upper and lower stalk guidingwheels of each of the at least two stalk guiders is disk-shaped andcomprises indentations at a periphery thereof.
 16. The stalked cropharvesting header according to claim 11, further comprising at least onelane determining element extending from a front end of the header in aforward driving direction, the at least one lane determining elementseparating the at least one harvesting unit from another harvesting unitin the forward driving direction.
 17. The stalked crop harvesting headeraccording to claim 16, wherein the upper stalk guiding wheels of the atleast two stalk guiders extend in the forward driving direction over adistance that is larger than a spacing between the at least one lanedetermining element and an adjacent lane determining element.
 18. Thestalked crop harvesting header according to claim 11, wherein thetransmission connecting the each of the first and second stalk cuttingwheels to the respective one of the at least two first gears is aplanetary gearbox.
 19. The stalked crop harvesting header according toclaim 11, wherein each of the at least two stalk guiders comprises aframe carrying the upper stalk guiding wheel and the lower stalk guidingwheel of the each of the at least two stalk guiders, the framecomprising a protrusion between the upper and the lower stalk guidingwheels of the each of the at least two stalk guiders, the protrusioncomprising a support for carrying a front end of a respective one of theat least two snapping rollers.